linux-kernel - Re: [PATCH 08/25] media: atmel: properly get pm

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Message-ID: <e25d024e-4fa6-dd67-b97a-1d2640f2b560@microchip.com>
Date:   Thu, 10 Jun 2021 12:00:42 +0000
From:   <Eugen.Hristev@...rochip.com>
To:     <mchehab+huawei@...nel.org>
CC:     <Jonathan.Cameron@...wei.com>, <linuxarm@...wei.com>,
        <mauro.chehab@...wei.com>, <alexandre.belloni@...tlin.com>,
        <Ludovic.Desroches@...rochip.com>, <mchehab@...nel.org>,
        <Nicolas.Ferre@...rochip.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <Claudiu.Beznea@...rochip.com>
Subject: Re: [PATCH 08/25] media: atmel: properly get pm_runtime

On 6/10/21 12:38 PM, Mauro Carvalho Chehab wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Em Thu, 10 Jun 2021 09:04:07 +0000
> <Eugen.Hristev@...rochip.com> escreveu:
> 
>>>> diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
>>>> index fe3ec8d0eaee..ce8e1351fa53 100644
>>>> --- a/drivers/media/platform/atmel/atmel-isc-base.c
>>>> +++ b/drivers/media/platform/atmel/atmel-isc-base.c
>>>> @@ -294,9 +294,13 @@ static int isc_wait_clk_stable(struct clk_hw *hw)
>>>>    static int isc_clk_prepare(struct clk_hw *hw)
>>>>    {
>>>>         struct isc_clk *isc_clk = to_isc_clk(hw);
>>>> +     int ret;
>>>>
>>>> -     if (isc_clk->id == ISC_ISPCK)
>>>> -             pm_runtime_get_sync(isc_clk->dev);
>>>> +     if (isc_clk->id == ISC_ISPCK) {
>>>> +             ret = pm_runtime_resume_and_get(isc_clk->dev);
>>>> +             if (ret < 0)
>>>> +                     return ret;
>>>> +     }
>>
>> Hi Mauro,
>>
>> With this patch, the ISC is broken on latest media tree. It looks like
>> pm_runtime_resume_and_get for the ISC_ISPCK clock returns -ENOACCESS and
>> thus, the probe of the driver fails:
>>
>> atmel-sama5d2-isc f0008000.isc: failed to enable ispck: -13
>> atmel-sama5d2-isc: probe of f0008000.isc failed with error -13
>>
>>
>> Could you point out how I could fix this ? Maybe the isc_clk->dev is not
>> properly handled/initialized in some other part of the code ?
> 
> Looking at RPM implementation:
> 
>          static int rpm_resume(struct device *dev, int rpmflags)
>          {
> ...
>          if (dev->power.runtime_error)
>                  retval = -EINVAL;
>          else if (dev->power.disable_depth == 1 && dev->power.is_suspended
>              && dev->power.runtime_status == RPM_ACTIVE)
>                  retval = 1;
>          else if (dev->power.disable_depth > 0)
>                  retval = -EACCES;
> ...
> 
> It sounds that RPM is disabled for this clock. Did you call
> pm_runtime_enable() before calling isc_clk_prepare()?
> 
> Thanks,
> Mauro
> 

I tried to call pm_runtime_enable for the clk at clk_init time, but 
doing that makes the runtime for the ISC fail like this:

atmel-sama5d2-isc f0008000.isc: Unbalanced pm_runtime_enable!